1. Field of the Invention
The present invention relates to housings for fan units, wherein the housings support a fan motor and define an air passage for guiding airflow induced by rotation of the fan motor. More particularly, the present invention relates to housings for fan units used for cooling central processing units (xe2x80x9cCPUsxe2x80x9d), circuit boards, and other electrical components disposed inside electrical apparatus, such as a personal computer or the like. The present invention also relates to an electrical apparatus using a fan unit for cooling CPUs, circuit boards, and other electrical components disposed therein.
2. Description of the Related Art
In electric apparatus, such as personal computers and game devices, fan units for exchanging air inside and outside the apparatus are used to cool CPUs, circuit boards, and other electrical components disposed inside the apparatus. One such motor is disclosed in U.S. Pat. No. 6,010,318.
FIGS. 1 and 2 show an example of a conventional fan unit 1 composed of a housing 5 and a fan motor 4. The fan motor 4 is supported by a plurality of supporting arms (not shown) extended from the housing 5, and an impeller 3 rotates about a rotational axis of the fan motor 4. As shown best in FIG. 2, the housing 5 includes a cylindrical section 5h and an air passage 5a defined by an inner peripheral wall of the cylindrical section 5h. The fan motor 4 is positioned within the air passage 5a by the supporting arms. A first flange 5g1 and a second flange 5g2, each having a rectangular planar shape, are each provided on a respective end of the cylindrical section 5h. One opening of the air passage 5a is defined as an air inlet 5b on the side of the first flange 5g1, and the other opening of the air passage 5a is defined as an air outlet (not shown) on the side of the second flange 5g2. Airflow induced by rotation of the impeller 3 of the fan motor 4 is guided from the air inlet 5b to the air outlet through the air passage 5a. The inner peripheral wall of the cylindrical section 5h has a tapered portion 5d provided at the opening on the side of the air inlet 5b, so that the airflow induced by rotation of the Impeller 3 can flow smoothly toward the inside of the air passage 5a. A plurality of screw holes 5c are formed on each of corners of the first and second flanges 5g1 and 5g2 so that screws (not shown) for mounting the fan unit 1 to a casing of an electrical apparatus, such as a personal computer, can be inserted therein.
The inside of the electrical apparatus upon which the fan unit 1 is mounted is heated to high temperatures by heat generated by the electrical components disposed therein, such as the CPU. In order to exhaust the heated air from the inside to the outside of the apparatus, the air inlet 5b faces the inside of the apparatus, and the air outlet is open to the outside of the apparatus. Thus, he heated air inside the electrical apparatus is exhausted to the outside by the fan unit 1 to thereby cool the electrical components disposed in the electrical apparatus.
It has become increasingly important for electrical apparatus, such as personal computers, to be more compact in size and to have lower power consumption. On the other hand, the performance of the electrical components used in these electrical apparatus, such as CPUs and the like, have been improved, and these components thereby tend to generate more heat. With the size reduction of the electrical apparatus, the spaces between the electrical components inside the electrical apparatus have been reduced, and as a result, the electrical components are more compactly and complexly arranged. As a result, the flow of air within the interior of the electrical apparatus is obstructed and the electrical components cannot be sufficiently cooled, thereby causing degradation of performance, such as calculation or processing speed, or resulting in breakdown of the electrical apparatus.
One approach to solving this problem has been to attempt to increase the size or rotational speed of the fan unit 1 to thereby increase the volume of airflow induced by the impeller 3. It has proven to be difficult to achieve this objective, however, due to the aforementioned requirements of reducing the size and power consumption of the electrical apparatus.
Accordingly, it is an object of the present invention to provide a housing for a fan unit having relatively high cooling efficiency.
It is another object of the present invention to provide a housing for a fan unit in which sufficient cooling performance can be obtained.
It is a further object of the present invention to provide a housing for a fan unit in which sufficient cooling performance can be obtained without increasing the size of the fan unit or the rotational speed of the fan motor.
It is a still further object of the present invention to provide a housing for a fan unit in which the direction of airflow induced by the rotation of the fan motor can be controlled.
It is another object of the present invention to provide an electrical apparatus wherein the interior of the apparatus is efficiently cooled by a fan unit.
It is still another object of the present invention to provide an electrical apparatus which achieves both stable operation and sufficient cooling of the electrical components disposed therein.
It is a further object of the present invention to provide an electrical apparatus in which the direction of airflow generated by a fan unit can be controlled.
In one aspect of the present invention, a housing for a fan unit includes an opening defined by an inner peripheral wall formed with an expanded section for enlarging a part of the opening in the radial direction with respect to the rotational axis of the fan motor, so that the speed of air flowing from a predetermined direction into the opening is higher than the speed of air flowing into the opening from other directions. Since a part of the opening is enlarged, the resistance to airflow at the expanded section of the opening is relatively low in comparison to other portions of the opening. Therefore, the airflow speed increases for the air flowing in the electrical apparatus from a predetermined direction toward the air inlet of the fan unit. As a result, a larger volume of air is thereby drawn into the air passage and is efficiently exhausted. By providing the expanded section at a position where electrical components having large heating values are disposed, such as a CPU or the like, a larger volume of air is drawn into the air passage from the region or side of the electrical components in comparison to the other regions or side of the apparatus and, in turn, is exhausted to the outside of the electrical apparatus. As a result, the inside of the electrical apparatus can be efficiently cooled without increasing the size of the fan unit or the rotational speed of the fan motor.
The expanded section may be defined by partially extending a tapered portion formed on either the air inlet or the air outlet side of the inner peripheral wall.
The foregoing and other objects, features, aspects and advantages of the present invention will become readily apparent from the following detailed description of preferred embodiments and accompanying drawings.